#include <iostream>
#include <string>
using namespace std;
int main()
{
    int score;
    string rank = "E";
    cout << "请输入成绩" << endl;
    cin >> score;
    switch (score / 10)
    {
    case 10:
        rank = "A";
        break;
    case 9:
        rank = "A";
        break;
    case 8:
        rank = "B";
        break;
    case 7:
        rank = "C";
        break;
    case 6:
        rank = "D";
        break;
    }
    cout << rank << endl;

}